1. Field of the Invention
The present invention relates generally to a face extraction from a moving picture or still image, and more particularly to an effective method for extracting the face using color distortion information.
2. Description of the Related Art
In various applications that use a digital moving picture or still image, such as a video indexing for providing a function of multimedia search, a human face is extracted and used in those applications.
As related arts, the conventional methods of extracting the face are as follows.
1. “Automatic Extraction of Face from Color Reversal Film Using Statistical Multi-step Filtering Technique” ACCV'95 Second Asian Conference On Computer Vision. December 5–8
2. Facelt (Visionics Corporation)
The technique of the first conventional methods relates to a method of searching a human face in a still image. According to this technique, an RGB color space is converted into an HSV color space, and then only pixels corresponding to a predefined skin color region are extracted.
The extracted skin color region is segmented after performing a post-processing such as an edge detection, a hole filling, or a gap filling operation, etc.
The segmented region is used for confirming the human face using a pattern prepared in advance for evaluation.
The second conventional technique is a tool kit having a function of automatically extracting the human face if the human moves on a camera screen and confirming whether he/she is a registered person and who he/she is.
The face extraction algorithm in this tool kit uses a method using a movement of an object and a neural network.
According to the second conventional technique, any color is not used, and thus any skin color information is not used.
However, most of face extraction algorithms such as the first conventional technique use the skin color information, and in actual applications, a range of the skin color is very broad in dependent of a medium of an image, environment, and illumination.
Accordingly, in a specified experimental environment, the skin color region can be determined and applied. However, in order to apply it to diverse moving picture media, a very broad region of the skin color should be determined, and thus certain region that is not the face may be extracted as the skin color region under certain circumstances.
However, since the skin color range of the face appearing in the same moving picture program or an image is not broad, the skin color region can be accurately extracted if a proper range can be determined. This is because the skin color region in the same images or moving pictures appears relatively regularly, since those images or moving pictures are photographed by the same medium and under the same environment.
However, when a certain still image or moving picture is given, a proper range of the skin color to match the given image among the entire skin color region cannot be automatically determined, and thus the above-described characteristic cannot be utilized.